Photographic film drive system employing inertia dumper

Abstract

Photographic processing and projector apparatus having a drive system including a gear train for advancing and rewinding the film on spools within a film cassette. Included in the gear train is an inertia dumper which is operative at the conclusion of a high speed rewind run to reduce film tension and cassette shock caused by the abrupt cessation of film movement at the end of the film.

What is claimed is: 
     
       1. Photographic apparatus for use with a film handling cassette, the cassette including a cassette housing retaining a photographic film strip and means for guiding the film strip along a given path within the cassette housing, said guiding means including at least one film spool to which one end of the film strip is attached and upon which the film strip is wound, the film strip being drawn from the film spool as the film strip is advanced in a given direction within said cassette housing, the film strip being subject to abrupt stoppage within the cassette housing when the film strip is advanced to the one end, and the film strip and the film guiding means having a high spring rate, said apparatus comprising means for receiving the cassette, means for cooperating with the cassette when it is received in said receiving means for driving the film strip in at least said given direction along the given path within the cassette housing, said film driving means including means for absorbing at least a large portion of the kinetic energy of said driving means when film stoppage occurs, said absorbing means comprising means having a substantially lower spring rate than that of the film strip and the film guiding means when the film strip is driven by said driving means in said given direction, said driving means including a drive train having a plurality of elements configured for rotation, said absorbing means including a spring configured for intercoupling a first and a second of said plurality of elements, said spring having a lower spring rate than the spring rate of the film strip, said first and second elements engaging respective ends of said spring so as to provide a driving connection through said spring when said drive train is rotated in a first direction configured for advancing the film strip in said given direction, and said first and second elements include means for engaging each other so as to provide a direct driving connection when said drive train is rotated in the opposite direction. 
     
     
       2. The apparatus of claim 1 wherein said absorbing means is a spring having a spring rate approximately 1/50 the spring rate of the film strip. 
     
     
       3. The apparatus of claim 1 wherein said first and second elements comprise first and second gears mounted on a common axis, one of said gears having means for axially spacing the other of said gears therefrom, and said engaging means comprises an abutment member carried on each of said gears, said abutment members being positioned on each of said gears so as to contact each other when one of said gears is rotated in said opposite direction. 
     
     
       4. The apparatus of claim 1 wherein said first and second elements comprise first and second gears mounted on a common axis, each of said gears having a flange-like body portion extending radially from said common axis, one of said gears having a tubular sleeve projecting axially therefrom and configured for engaging the body portion of the other of said gears so as to axially space said body portions from each other, said spring being a tortion spring loosely coiled about said sleeve, and said engaging means includes an abutment member carried on each of said gears, said abutment members being respectively positioned on each of said gears so as to be located within said sleeve and to contact each other when at least one of said gears is rotated in said opposite direction. 
     
     
       5. The apparatus of claim 1 wherein said first and second elements comprise first and second gears mounted for rotation about a common axis, each of said gears having a flange-like body portion, one of said gears having a tubular sleeve projecting axially therefrom and configured for engaging the body portion of said second gear so as to axially space said body portions of each of said gears from each other, said second gear having an axial bore therein, and said first gear further including an axle located within said sleeve and concentric thereto, said axle projecting from said body portion beyond the distal end of said sleeve and within said axial bore of said second gear such that said second gear is mounted for rotation on said first gear, said spring being loosely coiled about said sleeve with the ends of said spring in engagement with each of said gears respectively, and said engaging means includes an abutment member carried on each of said gears, said abutment members being respectively positioned on said body portions of said gears so as to be located within said sleeve and to contact each other when at least one of said gears is rotated in said opposite direction. 
     
     
       6. The apparatus of claim 5 wherein said axle extends through said second gear, and further including means coupled to the distal end of said axle for retaining said second gear in a rotational arrangement thereon. 
     
     
       7. Photographic apparatus for use with a cassette having a cassette housing, a pair of film spools rotatably supported within the cassette housing, and a strip of photographic film having a given spring rate wound on and extending between the film spools with the respective ends of the film strip affixed to the film spools, the film strip being configured for advancement within the cassette by winding the film strip on one film spool as it is unwound from the other film spool and subject to abrupt stoppage of advancement as the film strip reaches the film strip end affixed to the said other film spool, said apparatus comprising drive means for rotating said film spools, said drive means including first and second gears rotatable about a common axis, and a spring of substantially lower spring rate than such film strip disposed between said first and second gears, said spring having portions thereof engaging portions of said first and second gears to permit limited angular movement between said first and second gears and to establish a driving connection therebetween in at least one direction of rotation thereof, said spring having a substantially lower spring rate than the given spring rate of such film so that said spring absorbs the kinetic energy of said drive means when such film movement abruptly ceases as a result of film stoppage, and each of said first and second gears having an abutment member thereon, said abutment members being positioned to contact each other when said first and second gears are rotated in a second direction opposite to said one direction to thereby establish a direct drive transmitting connection between said gears during rotation in said second direction. 
     
     
       8. The apparatus of claim 7 further comprising a tubular housing mounted on said first gear and disposed around said common axis, said tubular housing projecting from said first gear toward said second gear, and said abutment members being located on said gears so as to be positioned within said tubular housing.